702-69-2

1. A THF solution of 1,4-cyclohexanedione monoethylene glycol ketal (13.90 g, 89.00 mmol) was slowly added to a solution of LHMDS (1.0 M solution of THF, 89.5 mL, 1.0 eq.) in THF (250 mL) over a time period of 15 minutes at -78 °C. 2. the reaction mixture was stirred at -78 °C for 34 min. 3. iodomethane (6.5 mL, 1.2 eq.) was added to the reaction mixture followed by stirring at -78 °C for 20 minutes and then at room temperature for 2 hours. 4. the reaction was quenched by addition of saturated NH4Cl solution (250 mL) and extracted with ether (3 x 250 mL). 5. Combine the organic phases, dry with MgSO4, filter and concentrate in vacuum. 6. 7-methyl-1,4-dioxa-spiro[4.5]decan-8-one (11.16 g, 74% yield) was purified by fast chromatography (eluent: pentane-ether, ratio from 4:1→3:1→2:1). 7. The spectral data of the product were in agreement with those reported in the literature (Pfau, M.; Jabin, I.; Revial, G. J. Chem. Soc, Perkin Trans. 1991, 1935).

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